Method of producing an opaque,light weight fabric and resultant fabric

ABSTRACT

A LIGHT WEIGHT SPUNBONDED POLYESTER FABRIC HAVING A WEIGHT OF ABOUT 1.2 TO 1.4 OZ./YD.2 HAS APPLIED THERETO A VERY THIN FILM OF OPAQUING MATERIAL CONSISTING OF A SELF-CROSSLINKING ACRYLIC EMULSION POLYMER OF A COLLOIDAL DISPERSION OF A VINYL CHLORIDE OR A POLYSILOXANE CONTAINING 20 TO 30% BY WEIGHT OF AN OPAQUING FILLER. ABOUT 1 OZ. OF DRY, OPAQUING SOLIDS IS APPLIED PER SQUARE YARD OF FABRIC.

United States Patent M Int. Cl. B32b 27/36, 27/20 US. Cl. 117138.8 F 4 Claims ABSTRACT OF THE DISCLOSURE A light Weight spunbonded polyester fabric having a weight of about 1.2 to 1.4 oz./yd. has applied thereto a very thin film of opaquing material consisting of a self-crosslinking acrylic emulsion polymer of a colloidal dispersion of a vinyl chloride or a polysiloxane containing 20 to 30% by weight of an opaquing filler. About 1 oz. of dry opaquing solids is applied per square yard of fabric.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to a method of treating light weight non-woven fabrics to provide opacity and to the fabrics so treated.

(2) Description of prior art Non-woven fabrics, such as spunbonded polyesters, have come into wide spread use because of their many unique properties. Thus, very light weight spunbonded fabrics have high tensile strength, excellent tear strength, non-raveling edges and superior dimensional stability. Because of such qualities they are widely used as apparel interliners, labels, base fabrics for books and wallcoverings, bags, electrical laminates and backings for leather or vinyl coated shoe linings.

Another interesting feature of non-woven fabrics is that they are very inexpensive to produce so that they show great promise for use as disposable articles. The main disadvantage of light weight non-woven fabrics is that they tend to be transparent, or at least translucent, and this greatly restricts the number and variety of their possible uses as disposable articles, eg for disposable garments, sheets, etc.

It is an object of this invention to provide a low cost method of opaquing such light weight non-Woven fabrics.

SUMMARY OF THE INVENTION According to our invention a light weight, non-woven fabric has applied thereto a very thin layer of an opaquing material comprising a fabric treating polymer emulsion or dispersion containing about 20 to 30% of an opaquing filler.

Among suitable fabrics to be treated there can be mentioned rayon, acetate, nylon and polyester. Spunbonded polyester fabrics made from crimped fibers have been found to be particularly suitable for articles of apparel and bed sheets because of their soft, comfortable hand. In order to keep the fabric cost as low as possible,

3,666,545 Patented May 30, 1972 a very light weight fabric should be used, e.g. one weighing about 1.2-1.4 oz./yd.

Almost any polymeric emulsion or dispersion which is available for treating fabrics of the above types can be used according to our invention. -'It is, of course, desirable to use polymers which have a very high curing rate at a low curing temperature. The high curing rate is important for low production costs, while some of the fabrics may contain heat sensitive fibers making low curing temperatures important.

Among suitable polymeric materials there can be mentioned colloidal dispersions of vinyl chloride polymers and copolymers in water and acrylic emulsion copolymers, particularly self-crosslinking acrylic polymers. Another polymer which can be used is a polysiloxane rubber which has the advantage of providing waterproofness to the fabric. These polymeric materials may or may not be preplasticized and if a separate plasticizer is necessary, this can be selected from a wide variety of commercially available agents.

It is particularly desirable to use plasticizers which will also impart flame resistance to the fabric, e.g. phosphates or antimonates. Tricresyl phosphate is a particularly good plasticizer which imparts to the fabric a durability against deterioration by washing and/or dry cleaning, while also imparting flame resistance. Another highly suitable plasticizer is a mixture of triand di-chloropropyl phosphate, which can be used together with di-ammonium phosphate to provide flame-proofing.

A wide variety of opaquing fillers can be used according to our invention. These include, inter alia, any one of, or any mutually compatible combination of, the fol lowing substances (1) Talc (2) A superflos (3) Clay (4) Blocks or powders of natural or synthetic fibers.

The superfios is a carbonate of silicon, magnesium aluminum or calcium and is available in the form of a very light powder having a very high covering power. Mixtures of such substances appear in the natural state, for example, in the mineral wollastonite.

As flocks or powders of natural or synthetic fibers there can be used flocks or powders of cellulosic fibers including cotton and rayon fibers or acrylic fibers.

The fillers may also contain additional ingredients including extenders, dispersing agent and pigments.

Among suitable extenders there can be mentioned a synthetic silicate, for example, a hydrous calcium silicate produced by the hydrothermal reaction of diatomaceous silica and lime or magnesium. The extender is chosen with the view to the subsequent treatment to which the fabric is to be exposed. For example, if it is to be subjected to a form of printing that uses a water based colouring, then a grade of extender is selected having a high water absorption (e.g. 500% or more), whereas, if an oil based printing step is followed, a grade of extender is selected having a high oil absorption (e.g. also about 500%). The extender then acts to suck up and firmly hold the colouring matter and thus gives the finished product a bright, fully coloured appearance.

As dispersing agents, organic dispersants can be used as well as inorganic agents, such as potassium tetraphosphate.

The pigments can be selected freely depending on the desired finish of the fabric. If the fabric is to be white, 21 rutile grade of titanium dioxide may be used, While if a shiny or silk-like surface is desired a synthetic pearl pigment, such as guanine, can be used. When the filler contains acrylic flocks, particularly vibrant colours can be obtained with cationic dyes.

A thin film of most of the opaquing materials can best be applied by means of a roller, such as an engraved roller, or kiss roller or by means of a doctor blade. For this type of application the opaquing material must be reasonably viscouse, e.g. 7,000 and higher Brookfield viscosity, and this may require the addition of a thickener. Among very satisfactory thickeners there can be mentioned bydroxyethyl cellulose.

After the film has been applied, the fabric is dried by passing it over calender rolls and through a drying chamher at temperatures up to about 300 F.

It is an important feature of the invention that a very thin and even layer of opaquing material be applied to the fabric. This is important both for manufacturing costs and the softness of the finished fabric. Generally only about 1-2, ounces of opaquing material dry solids are applied per square yard of fabric and about 1-1.5 ounces are particularly desirable.

When the fabric is being coated with a polysiloxane rubber containing fillers, this can successfully be applied from a relatively thin solution in a padding bath. The fabric treated in this manner is dried in a conventional pin stander at a temperature of up to 300 F. The polysiloxane treated fabric is waterproof and is particularly useful for making disposable sheets for hospital beds.

Working examples The invention is illustrated by the following Working examples:

' EXAMPLE 1 An opaquing composition was prepared having the following ingredients, all percentages being by weight.

Percent Polyvinyl chlon'de latex (Geon) 40 Tricresyl phosphate 10 Filler-mixture of 10% talc, 12% superflos and 3% extender plus a small amount of tetraphosphate as a dispersing agent 25 Hydroxyethyl cellulose l-S Water, balance to 100%.

This composition was then used to provide opaquing to a spunbonded polyester fabric available under the trademark Reemay. The fabric had a thickness of 10 mils and a weight of 1.2 oz./yd.

The opaquing composition was applied to the fabric by means of an engraved roller at room temperature and a fabric speed of 50 yd./min. The treated fabric was dried by passing over calender rolls and through a hot chamber for 3 minutes at temperatures up to 300 F. About 1.1 oz. of dry solids were deposited per square yard of fabric.

The finished fabric showed excellent opacity and was readily dyeable to any desired colour.

EXAMPLE 2 An opaquing composition was prepared having the following ingredients, all percentages being by Weight:

Percent Self-crosslinking acrylic polymer (Rhoplex TIA-8) 50 Triand di-chloropropyl phosphate 7 Filler-mixture of 20% superflos, 3% talc and 2% extender plus small amount of potassium tetraphosphate as a dispersing agent 25 Hydroxyethyl cellulose 1 Oil and water repellent (Scotchgard 212 F) 2-4 Liquid ammonia to adjust pH to 8 Trace Water, balance to 100%.

4 This composition was also used to coat Reemay fabric under the same conditions as in Example 1. Again excellent opacity was obtained.

EXAMPLE 3 Another opaquing composition was prepared having the following ingredients:

The batch was made up to 10 Imperial gallons and the pH was adjusted to 8 with ammonia.

Reemay fabric was coated with the above composition under the same conditions as in Example 1 and once again excellent opacity was obtained.

EXAMPLE 4 An opaquing composition was prepared having the following ingredients, all percentages being by weight:

Percent Water 43.0 Cellulose fibre powder 25.0

Acrylic polymer (experimental emulsion 13-485) 30.0

Sodium salt of carboxylated polyelectrolyte (Tomol) 0.2 Hydroxyethyl cellulose 1.8

The pH was adjusted to 8 with ammonia and the composition was used to treat Reemay according to the procedure of Example 1. Excellent opacity was obtained.

EXAMPLE 5 An opaquing composition was prepared having the following ingredients, all percentages being by Weight:

Percent Dimethyl polysiloxane (Dow Corning 236 dispersion) TiO Organic solvent, balance.

This composition was applied to Reemay fabric by passing the fabric through a padding bath. The wet chemical pick-up was about 40 and the treated fabric was dried in a conventional pin stander at temperatures up to 300 F.

The dried, treated fabric was not only opaque but was also waterproof, making it excellent material for disposable hospital sheeting.

We claim:

1. A method of producing an opaque, light weight, disposable fabric which comprises applying to a spunbonded polyester fabric having a weight of 1.2 to 1.4 oz./yd. a thin layer of an opaquing composition comprising a polymeric emulsion or dispersion selected from the group consisting of a colloidal dispersion of vinyl chloride polymers, acrylic emulsion polymers and polysiloxanes containing 2030% by weight of opaquing filler, the opaquing composition having a Brookfield viscosity of about 7000 to 8000 and being applied by means of an engraved roller, and drying the coated fabric to provide a layer of about 1-2 ounces of dry solids per square yard of fabric.

2. An opaque, spunbonded polyester fabric obtained by the method of claim 1.

3. A method of producing an opaque, light weight, disposable fabric which comprises applying to a spunbonded polyester fabric having a weight of 1.2 to 1.4 ore/yd. a thin layer of an opaquing composition comprising a selfcrosslinking acrylic fabric treating polymer containing 20-30% by weight of opaquing filler, the opaquing composition having a Brookfield viscosity of about 7000 to 8000 and being applied by means of an engraved roller, and drying the coated fabric to provide a layer of about 1-1.5 ounces of dry solids per square yard of fabric.

4. A method of producing an opaque, light weight, disposable fabric which comprises applying to a spunbonded polyester fabric having a weight of 1.2 to 1.4 oz./yd. a thin layer of an opaquing composition comprising a fabric treating colloidal water dispersion of vinyl chloride copolymer containing 20-3 by weight of opaquing fillers, the opaquing composition having a Brookfield viscosity of about 7000 to 8000 and being applied by means of an engraved roller, and drying the coated fabric to References Cited UNITED STATES PATENTS 2,626,941 1/ 1953 Habeck 26041 A 2,881,146 4/1959 Rerner et a1. 117139.5 A 3,077,460 2/1963 Fortess l17-139.5 A 3,248,314 4/1966 Nahin 2604l A 3,009,822 11/1961 Drelich et al. 11738 3,228,790 1/1966 Sexsmith et al 11738 X 3,274,018 9/1966 Russell et a1. 11738 X RALPH HUSAOK, Primary Examiner US. Cl. X.R.

provide a layer of about 1-1.5 ounces of dry solids per 15 117-38, 136, 138.8 N, 139.5 A, A, 145, 161 UC,

square yard of fabric.

2 A, UP; 161-6 

